1. Field of The Invention
The present invention relates to pole extension systems and, more particularly, to systems for connecting an extension pole to a main pole used, for example, in the large size pole of a "garden umbrella".
2. Background Art
In many applications where long poles are employed, such as in the garden umbrella, a two piece pole is attached together to provide the full pole length required. Use of the two piece pole facilitates the shipping, use and storage of the umbrella and the pole since the pole length is reduced to 50% of the fur pole length. Where, for example, an 8 foot long pole is required the umbrella, use of two 4 foot sections of pole connected together greatly reduces the length of the overall umbrella size at those times other than when the umbrella is open. One problem found in the conventional umbrella poles is that there is a significant amount of play or relative movement between the main pole and its extension pole. This play is due to the loose connection means used between the main pole and its extension
In the commonly known extension poles, a main pole has a thredded screw or nut attached at its end, while the extension pole has a mating nut or screw at its end for attachment to the mating screw or nut, respectively, at the end of the main pole. One problem with this connection is that the the screw and nut joint becomes a pressure point for the pole, resulting in a loosening of the screw and nut from their pole connections, as well as unscrewing and loosening of the connection after a certain amount of use. Another type of pole connection, often used with aluminum garden umbrella poles, consists of hollow aluminum poles sized to fit, one within the other at their ends with a pop-up locking button that extends from the inner pole through a hole in the outer pole to thereby lock the poles against relative movement. The problem with this pop-up button type of connection is that the button becomes the pressure joint for the connection and cannot provide a tight, rigid connection so as to prevent the poles from twisting and relative movement. Another problem with the pop-up locking button is that the it may become a tedious task to set the button from one pole to fit into the hole in the other pole. The problems with the above-described known extension pole connections is the looseness and play between the poles may limit the stability and durability of the pole and extension, and in some cases such as that of an umbrella pole, may result in damage to the umbrella. Other known pole extension devices are complex and relatively expensive.